1. Field of the Invention
The invention relates to a continuous motion assembly apparatus. More specifically, this invention relates to an apparatus for assembling devices comprising a plurality of parts wherein one of the parts is mounted on another one of the parts by a continuously variable amount.
2. Description of Prior Art
Automatic assembly apparatus for assembling multi-part devices, such as ball point pens, lipstick cases, syringes, etc., are well known. Such devices are usually made up of a main part and further parts assembled with the main part to make up the device, and in the known apparatus, the parts to be assembled are conveyed to an assembly station, the conveyor system is stopped, the parts are assembled, and the conveyor system starts up again to bring the assembled part to a further assembly station where further parts are added. The different parts may be carried by different conveyors, in which case, all the conveyors will have to be stopped for all assembly activities.
For example, in assembling a non-retractable ball point pen, the pen barrel would be the main part, and this would be brought to an assembly station by a conveyor. The nib and ink carrying arrangement would also be brought to this station by a conveyor, or it may be dispensed there by a dispenser unit. While the nib is being inserted into the barrel, the conveyor or conveyors would have to be stopped. The assembled barrel and nib would then be conveyed to a second station to which end stoppers are also conveyed. Again, the conveyors must be stopped while the end stopper is mounted on the end of the barrel remote from the nib.
Of course, the various assembly activities will be taking place at the same time, i.e., while an end stopper is being mounted on barrel number 2, a nib is being inserted in barrel number 1, etc.
With the known apparatus, the motion between stations must be carefully indexed, i.e., it is critical that the end stopper which is to be mounted on a barrel be directly adjacent the barrel. This requires precision tooling and machining of the indexing means. In addition, the start and stop motion of the known apparatus limits the speed at which the apparatus can operate and, therefore, the production speed of the apparatus.